1. Technical Field
The present invention relates to a printing apparatus in which liquid is discharged through a head held in a carriage, and thus an image is printed on a recording medium.
2. Related Art
In recent years, a printing apparatus, such as an ink jet printer, in which liquid is discharged through nozzles of a head in a state where the head faces a supporting member that supports a recording medium, and thus an image is printed on the recording medium has been known. Generally, in such a printing apparatus, not only a printing operation described above can be performed but also maintenance, such as elimination of nozzle clogging, can be performed on the head by a maintenance unit.
To perform high-quality printing of a printing apparatus, it is necessary to position each head at a position, that is, a vertical position, predetermined relative to the supporting member in a liquid discharging direction. In addition, when maintenance is performed, it is necessary to position the head at a vertical position suitable for performing the maintenance. For this reason, the printing apparatus of the related art is equipped with a unit which regulates a vertical position of the head by moving the head in an up-down direction. In an apparatus disclosed in, for example, JP-A-2009-274285, guiding mechanisms are respectively provided on both longitudinal end portions of a head holder (corresponding to a “carriage” according to an aspect of the invention) and a head can move in an up-down direction, relative to the head holder. More specifically, the apparatus described above is configured as follows.
In the apparatus disclosed in JP-A-2009-274285, the guiding mechanisms having the same configuration are respectively provided on the end portions such that the head holder is pinched between both longitudinal end portions. Each guiding mechanism has two guide rails which are installed in a superimposed state. One of the guide rails is fixed to the head holder and the other guide rail supports the head and is slidable along the one guide rail. When a stepping motor is operated, the other guide rail moves along one guide rail, and thus the head moves and is positioned.
To perform favorable printing, high-accuracy positioning is required for a head. Thus, it is necessary to use a high-precision guide rail. Therefore, in the case of the apparatus disclosed in JP-A-2009-274285, it is necessary to use high-precision guide rails as both guiding mechanisms. As a result, the following problems may be caused. As the precision of the guiding mechanism increases, precision at a high level, for example, at a level of several μm, is required for a mounting process. Accordingly, it is necessary for both longitudinal end portions of the head holder to satisfy the requirement described above. When at least either of the longitudinal end portions does not satisfy the requirement described above, stress, such as torsion and tilting, acting in a direction other than an operation direction is caused due to the guiding mechanisms, both of which have a high positioning accuracy. Thus, there is possibility that a movement operation of the head may become heavy or, in the worst case, the guiding mechanism may be damaged. Accordingly, it is necessary for all components on which the guiding mechanism is installed to have very high surface accuracy, positional accuracy, or the like, and this is one of the main factors of an increase in cost.